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The Build-up of the Red Sequence in High Redshift Galaxy Clusters

Pierluigi Cerulo (CAS), Warrick J. Couch (AAO), Chris Lidman (AAO)

+HAWK-I Cluster collaboration

pcerulo@astro.swin.edu.au

INAF Ossevatorio Astronomico di Capodimonte18 November 2015

Outline of the Talk

1) Introduction: galaxy evolution and environment, clusters of galaxies

2) The Sample: the HAWK-I Cluster Survey (HCS)

3) Results: i) the Build-up of the Red Sequence in the HCS ii) Morphological Evolution of Red Sequence Galaxies iii) Formation Age of the Red Sequence (work in progress)

4) Summary and Future Directions

Clusters of Galaxies as Cosmic Laboratories

Abell 370 (z=0.375)

GOODS South Field

The colour-magnitude diagram

Cerulo et al. (2015a, submitted.)

The Build-up of the Red Sequence at z ~ 1

The Evolution of the Cluster Red Sequence

Merson et al. (2015)

Romeo et al. (2008)

Romeo et al. (2015)

The Role of Stellar Mass

ClG 0218 (z=1.62)

Rudnick et al. (2012)

The Scientific Questions

1) What are the processes responsible for the build-up of the red sequence in clusters of galaxies?

2) What are the evolutionary paths followed by galaxies with different morphologies on the red sequence?

3) When was the red sequence built up?

The HAWK-I Cluster Survey (HCS)

Lidman et al. (2013)Delaye et al. (2014)Cerulo et al. (2014)

Credit ESO

Credit: Pablo McLoud

Credit: Gemini Observatory

The WIde-field Nearby Galaxy cluster Survey(WINGS)

Abell 119 (z=0.044)

- 78 clusters at 0.04 < z < 0.08 imaged in up to 5 bands from near-UV (U) to near-IR (K) (Fasano et al. 2006)- 48 clusters followed up spectroscopically with WHT and the AAT (WINGS-SPE, Cava et al. 2009)

Catalogues and data are publicly available

http://www.aao.gov.au/about-us

Credit: A. Tudorica/ESO

RCS0220 (z=1.03)

RCS2319 (z=0.91)

RX0152 (z=0.84)

RCS2345 (z=1.04)

XMMU0223 (z=1.22)XMM1229 (z=0.98)

RDCS1252 (z=1.24)

XMMU2235 (z=1.39)

XMMXCS2215 (z=1.46)

The Build-up of the Cluster Red Sequence(Cerulo et al. 2015a submitted)

The Evolution of the Colour-Magnitude RelationI : red sequence zero-point (average colour)

Cerulo et al. (2015a) submitted

The Evolution of the Colour-Magnitude RelationII : red sequence slope

Cerulo et al. (2015a) submitted

The Evolution of the Colour-Magnitude RelationII : red sequence slope

Cerulo et al. (2015a) submitted

The Accelerated Build-up of the Cluster Red Sequence

The build-up of the red sequence in clusters (black symbols) is accelerated with respect to the field (blue symbols) at low stellar masses=> halo mass sets the time-scales for star-formation quenching and red sequence assembly (Cerulo et al. 2015a submitted)

The Accelerated Build-up of the Cluster Red Sequence

Haines et al. (2008)Clusters vs Field at z = 0

Cerulo et al. (2015a) submitted

The Red Sequence in Low and High Mass Clusters

Cerulo et al. (2015a) submitted

The bright end of the red sequence (Mv < -22.0 mag) appears more developed in high halo mass clusters.

S0

Late-type spirals +

irregulars

Ellipticals

Early-type spirals

- Visual + automated classification

- 4 independent classifications (3 visual + 1 software-based)

- Used ACS F850LP images and only galaxies with F850LP < 24.0 mag

- Automated classification performed using galSVM(Huertas-Company et al. 2008, 2011)

The Morphological Transformations of Red Sequence Galaxies

(Cerulo et al. 2015b in prep.)

See Cerulo et al. (2014) for details on morphological classification.

Morphological Evolution

Cerulo et al (2015b) in preparation

Morphological Evolution

Cerulo et al (2015b) in preparation

Elliptical galaxies dominate the red sequence at z=1, while the red sequence of the low-z comparison sample is dominated by elliptical galaxies at the bright end and by S0 galaxies at the faint end => faint S0 galaxies joined the red sequence at later epochs and are probably the result of the morphological transformation of quiescent spiral galaxies (red spirals).

See Cerulo et al. (2014) for a discussion on the bright elliptical galaxies in WINGS

Spectral Properties of Red Sequence Galaxies with Different Morphologies

Elliptical Galaxies

S0 Galaxies

RCS0220 (z=1.03) (GMOS-N)

WARNING: VERY PRELIMINARY!!!! ANALYSIS STILL ONGOING

S0 spectra (see CaII H and K lines, Rose 1985 Index) indicate that these galaxiesmay host younger stellar populations with respect to elliptical galaxies on the red sequence => S0 have a different, more recent origin

Morphological Evolution of Galaxies

Mei et al. (2009)

Tran et al. (2007)

0.8 < z < 1.3

Z=0.8

The Age-Scatter Test(Bower, Lucey & Ellis 1992)

The Age-Scatter Test(Bower, Lucey & Ellis 1992)

Romeo A., Cerulo P. et al. in preparation

The Age-Scatter Test(Bower, Lucey & Ellis 1992)

Summary and Conclusions

The red sequence of galaxy clusters appears to be already assembled at z=1.5 with a negative slope as observed at lower redshifts

The red sequence in the HCS clusters underwent an accelerated build-up

The most massive HCS clusters host a population of massive red sequence galaxies 0.5-1.0 mag brighter than the rest of the red sequence

The cluster red sequence at z~1 is dominated by elliptical galaxies at all luminosities and stellar masses, while at z~0.05 S0 galaxies become the predominant population at Mv > -21.0 mag

S0 galaxies seem to host younger stellar populations compared to elliptical galaxies <= VERY PRELIMINARY RESULT

Future Directions

Analysis of stellar populations on the HCS red sequence;

analysis of the infall regions (preprocessing);

collaboration with theoretical astrophysicists to allow a coherent picture of galaxy evolution in clusters to be built.

Co-evolution of Structure and Stellar Populations in Galaxies

Nantais et al. (2013) Fritz et al. (2014)

Thank you